Antibiotic transport and accumulation: concepts and methodologies
Muriel Masi, Julia Vergalli, Jean-Marie Pagès
Axis 2: Molecular mechanisms of impermeability and efflux
MCT develops methodologies to understand how bacterial membrane transporters regulate the intracellular accumulation of antibiotics and other chemicals. By controlling drug influx and efflux, these transporters determine drug concentration and efficacy within bacterial cells, emphasizing the need to study bacterial permeability comprehensively.
The RTC2T (Resident Time Concentration Close to its Target) concept measures the intracellular concentration of antibacterial drugs near their target, thus enabling the study of resistance mechanisms that limit drug accumulation. The SICAR (Structure Intracellular Concentration Relationship) concept evaluates antibiotics’ affinity for membrane transporters (i.e., efflux pumps and porins), linking their behavior to translocation efficacy and accumulation. SICAR indices guide structural improvements based on antibiotics’ interactions with transporters.
Collaborations between MCT and Synchrotron SOLEIL have produced innovative methods using antibiotic fluorescence properties to study drug accumulation in intact cells. Spectrofluorimetry measures intracellular drug concentrations after cell lysis, while deep-UV (DUV) microscopy quantifies accumulation in individual bacteria over time. Despite some limitations, these methods are more reliable, sensitive, and adaptable than traditional assays like MIC determination.
MCT’s advanced methodologies track and quantify antibiotic concentration near bacterial targets. To further develop drug accumulation monitoring, MCT uses three technologies: spectrofluorimetry (MCT microbiology laboratory), LC-MS/MS (MAP-PIT2 Platform), and high-resolution imaging (MALDI-MSI on MAP-PIT2, DUV microfluidics at SOLEIL, and cryo X-ray fluorescence at the ESRF).
